Edge effects and submicron tracks in magnetic tape recording

Edge Effects and Submicron Tracks in Magnetic Tape Recording As track widths in magnetic tape recording are approaching few micrometers, increasingly better control of the track edges is required. This thesis is concerned with the investigation of the recording process in narrow tracks down to the submicron range, with emphasis on edge effects. Side writing and erasing were primarily treated, as they represent critical limitations for increasing the track density. Side reading was also addressed, however, it is not considered to be a severe issue for modern tape storage systems. Diverse investigation methods were applied and explored, including track profiling techniques and magnetic force microscope (MFM) imaging. A novel triple-track profiling model able to assess erase bands down to 0.2 µm and below was introduced, as well as an original technique for studying the recording process in submicron tracks, based on microtrack measurements. The principles for developing a recording tester with ultimate performances aimed at track widths below 0.5 µm were also laid down. Narrow track recording and edge effects were analyzed using advanced Helical Scan Silicon (HSS) heads and MIG heads with pole widths from 1.3 µm to 6.2 µm. Various ME and MP tapes were employed, having the thickness of the magnetic layer between 50 nm and 300 nm. The HSS heads were shown to write narrow tracks with well defined edges due to the good alignment of their poles and short gap lengths. Erase bands within 0.25 µm were measured at very short recording wavelengths down to 0.2 µm, for a HSS head with 0.11 µm gap length. They were obtained using a ME tape with thin recording layer of 50 nm and coercivity of 164 kA/m, being the thinnest erase bands reported to date in tape recording. It is demonstrated that good control of side writing and erasing is achieved using well aligned heads with short gap length and thin recording layers with high coercivity.